Dishwashing appliance and siphoning prevention

ABSTRACT

A dishwashing appliance may include a cabinet, a tub, a spray assembly, a drain pump, and a controller. The tub may be positioned within the cabinet and define a wash chamber. The spray assembly may be positioned within the wash chamber. The drain pump may be in fluid communication with the wash chamber. The controller may be configured to initiate a washing operation. The washing operation may include activating the drain pump for an activation period, deactivating the drain pump for a deactivation period, detecting a first water condition upstream from the drain pump during the deactivation period, detecting, following detecting the first water condition, a second water condition upstream from the drain pump during the deactivation period, comparing the second water condition to the first water condition, and directing the drain pump based on the comparison of the second water condition to the first water condition.

FIELD OF THE INVENTION

The present subject matter relates generally to dishwashing appliances and more particularly to methods or features for detecting or preventing a siphoning action at the dishwashing appliance.

BACKGROUND OF THE INVENTION

Dishwashing appliances generally include a tub that defines a wash chamber. Rack assemblies can be mounted within the wash chamber of the tub for receipt of articles for washing. Multiple spray assemblies can be positioned within the wash chamber for applying or directing wash fluid (e.g., water, detergent, etc.) towards articles disposed within the rack assemblies in order to clean such articles. Dishwashing appliances are also typically equipped with one or more pumps, such as a circulation pump or a drain pump, for directing or motivating wash fluid from the wash chamber (e.g., to the spray assemblies or an area outside of the dishwashing appliance).

Conventional dishwashing appliances include one or more drain lines extending from a sump portion of the wash chamber to direct water or wash fluid from the wash chamber. During use, and following a rinse or wash cycle of a washing operation, the drain pump may be selectively activated to draw water through the drain line. Subsequently, fresh water or wash fluid can be added to the wash chamber. In some instances, it may be possible for a siphoning condition to arise wherein water or wash fluid continues to be drawn through the drain line even though the drain pump is no longer active or activated. This can be especially problematic if water or wash fluid is simultaneously being added to the wash chamber, since such fluids will be siphoned away from the wash fluid instead of being circulated through the appliance. This may cause the circulation pump (or a heater assembly) to operate under a dry condition wherein insufficient or no water or wash fluid is present. Under some conditions, one or more elements of the dishwashing appliance may be damaged.

As a result, it would be useful for a dishwashing appliance to include one or more features to detect or even prevent siphoning conditions from occurring therein.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In one exemplary aspect of the present disclosure, a dishwashing appliance is provided. The dishwashing appliance may include a cabinet, a tub, a spray assembly, a drain pump, and a controller. The tub may be positioned within the cabinet and define a wash chamber for receipt of articles for washing. The spray assembly may be positioned within the wash chamber. The drain pump may be in fluid communication with the wash chamber. The controller may be in operative communication with the drain pump. The controller may be configured to initiate a washing operation. The washing operation may include activating the drain pump for an activation period, deactivating the drain pump for a deactivation period, detecting a first water condition upstream from the drain pump during the deactivation period, detecting, following detecting the first water condition, a second water condition upstream from the drain pump during the deactivation period, comparing the second water condition to the first water condition, and directing the drain pump based on the comparison of the second water condition to the first water condition.

In another exemplary aspect of the present disclosure, a method of operating a dishwashing appliance is provided. The method may include activating a drain pump for an activation period and deactivating the drain pump for a deactivation period. The method may further include detecting a first water condition upstream from the drain pump during the deactivation period; and detecting, following detecting the first water condition, a second water condition upstream from the drain pump during the deactivation period. The method may still further include comparing the second water condition to the first water condition and directing the drain pump based on the comparison of the second water condition to the first water condition.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

FIG. 1 provides a perspective view of an exemplary embodiment of a dishwashing appliance of the present disclosure with a door in a partially open position.

FIG. 2 provides a side, cross sectional view of the exemplary dishwashing appliance of FIG. 1 .

FIG. 3 provides a close up, cross sectional view of a sump and a pressure sensor of the dishwashing appliance of FIGS. 1 and 2 .

FIG. 4 provides a flow chart of a method of operating a dishwashing appliance, according to an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “includes” and “including” are intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). In addition, here and throughout the specification and claims, range limitations may be combined or interchanged. Such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “generally,” “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components or systems. For example, the approximating language may refer to being within a 10 percent margin (i.e., including values within ten percent greater or less than the stated value). In this regard, for example, when used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction (e.g., “generally vertical” includes forming an angle of up to ten degrees in any direction, such as, clockwise or counterclockwise, with the vertical direction V).

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” In addition, references to “an embodiment” or “one embodiment” does not necessarily refer to the same embodiment, although it may. Any implementation described herein as “exemplary” or “an embodiment” is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

The terms “upstream” and “downstream” refer to the relative flow direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the flow direction from which the fluid flows, and “downstream” refers to the flow direction to which the fluid flows.

Generally, the present disclosure may provide dishwashing appliances and methods to detect and address a siphon condition that can arise, for instance, at a drain pump. For instance, certain predetermined changes in sump pressure (e.g., after a drain pump has been deactivated) may indicate a siphon condition. If such changes are detected, the drain pump may need to, for instance, temporarily reactivating the drain pump to stop the siphon condition.

Turning now to the figures, FIGS. 1 and 2 depict an exemplary dishwasher or dishwashing appliance (e.g., dishwashing appliance 100) that may be configured in accordance with aspects of the present disclosure. Generally, dishwasher 100 defines a vertical direction V, a lateral direction L, and a transverse direction T. Each of the vertical direction V, lateral direction L, and transverse direction T are mutually perpendicular to one another and form an orthogonal direction system.

Dishwasher 100 includes a cabinet 102 having a tub 104 therein that defines a wash chamber 106. As shown in FIG. 2 , tub 104 extends between a top 107 and a bottom 108 along the vertical direction V, between a pair of side walls 110 along the lateral direction L, and between a front side 111 and a rear side 112 along the transverse direction T.

Tub 104 includes a front opening 114. In some embodiments, a door 116 hinged at its bottom for movement between a normally closed vertical position, wherein the wash chamber 106 is sealed shut for washing operation, and a horizontal open position for loading and unloading of articles from dishwasher 100. A door closure mechanism or assembly 118 may be provided to lock and unlock door 116 for accessing and sealing wash chamber 106.

In exemplary embodiments, tub side walls 110 accommodate a plurality of rack assemblies. For instance, guide rails 120 may be mounted to side walls 110 for supporting a lower rack assembly 122, a middle rack assembly 124, or an upper rack assembly 126. In some such embodiments, upper rack assembly 126 is positioned at a top portion of wash chamber 106 above middle rack assembly 124, which is positioned above lower rack assembly 122 along the vertical direction V.

Generally, each rack assembly 122, 124, 126 may be adapted for movement between an extended loading position (not shown) in which the rack is substantially positioned outside the wash chamber 106, and a retracted position (shown in FIGS. 1 and 2 ) in which the rack is located inside the wash chamber 106. In some embodiments, movement is facilitated, for instance, by rollers 128 mounted onto rack assemblies 122, 124, 126, respectively.

Although guide rails 120 and rollers 128 are illustrated herein as facilitating movement of the respective rack assemblies 122, 124, 126, it should be appreciated that any suitable sliding mechanism or member may be used according to alternative embodiments.

In optional embodiments, some or all of the rack assemblies 122, 124, 126 are fabricated into lattice structures including a plurality of wires or elongated members 130 (for clarity of illustration, not all elongated members making up rack assemblies 122, 124, 126 are shown in FIG. 2 ). In this regard, rack assemblies 122, 124, 126 are generally configured for supporting articles within wash chamber 106 while allowing a flow of wash fluid to reach and impinge on those articles (e.g., during a cleaning or rinsing cycle). According to additional or alternative embodiments, a silverware basket (not shown) is removably attached to a rack assembly (e.g., lower rack assembly 122), for placement of silverware, utensils, and the like, that are otherwise too small to be accommodated by the rack assembly.

Generally, dishwasher 100 includes one or more spray assemblies for urging a flow of fluid (e.g., wash fluid) onto the articles placed within wash chamber 106.

In exemplary embodiments, dishwasher 100 includes a lower spray arm assembly 134 disposed in a lower region 136 of wash chamber 106 and above a sump 138 so as to rotate in relatively close proximity to lower rack assembly 122.

In additional or alternative embodiments, a mid-level spray arm assembly 140 is located in an upper region of wash chamber 106 (e.g., below and in close proximity to middle rack assembly 124). In this regard, mid-level spray arm assembly 140 may generally be configured for urging a flow of wash fluid up through middle rack assembly 124 and upper rack assembly 126.

In further additional or alternative embodiments, an upper spray assembly 142 is located above upper rack assembly 126 along the vertical direction V. In this manner, upper spray assembly 142 may be generally configured for urging or cascading a flow of wash fluid downward over rack assemblies 122, 124, and 126.

In yet further additional or alternative embodiments, upper rack assembly 126 may further define an integral spray manifold 144. As illustrated, integral spray manifold 144 may be directed upward, and thus generally configured for urging a flow of wash fluid substantially upward along the vertical direction V through upper rack assembly 126.

In still further additional or alternative embodiments, a filter clean spray assembly 145 is disposed in a lower region 136 of wash chamber 106 (e.g., below lower spray arm assembly 134) and above a sump 138 so as to rotate in relatively close proximity to a filter assembly 210. For instance, filter clean spray assembly 145 may be directed downward to urge a flow of wash fluid across a portion of filter assembly 210 (e.g., first filter 212) or sump 138.

The various spray assemblies and manifolds described herein may be part of a fluid distribution system or fluid circulation assembly 150 for circulating wash fluid in tub 104. In certain embodiments, fluid circulation assembly 150 includes a circulation pump 152 for circulating wash fluid in tub 104. Circulation pump 152 may be located within sump 138 or within a machinery compartment located below sump 138 of tub 104.

When assembled, circulation pump 152 may be in fluid communication with an external water supply line (not shown) and sump 138. A water inlet valve 153 can be positioned between the external water supply line and circulation pump 152 (e.g., to selectively allow water to flow from the external water supply line to circulation pump 152). Additionally or alternatively, water inlet valve 153 can be positioned between the external water supply line and sump 138 (e.g., to selectively allow water to flow from the external water supply line to sump 138). During use, water inlet valve 153 may be selectively controlled to open to allow the flow of water into dishwasher 100 and may be selectively controlled to cease the flow of water into dishwasher 100. Further, fluid circulation assembly 150 may include one or more fluid conduits or circulation piping for directing wash fluid from circulation pump 152 to the various spray assemblies and manifolds. In exemplary embodiments, such as that shown in FIG. 2 , a primary supply conduit 154 extends from circulation pump 152, along rear 112 of tub 104 along the vertical direction V to supply wash fluid throughout wash chamber 106.

In some embodiments, primary supply conduit 154 is used to supply wash fluid to one or more spray assemblies (e.g., to mid-level spray arm assembly 140 or upper spray assembly 142). It should be appreciated, however, that according to alternative embodiments, any other suitable plumbing configuration may be used to supply wash fluid throughout the various spray manifolds and assemblies described herein. For instance, according to another exemplary embodiment, primary supply conduit 154 could be used to provide wash fluid to mid-level spray arm assembly 140 and a dedicated secondary supply conduit (not shown) could be utilized to provide wash fluid to upper spray assembly 142. Other plumbing configurations may be used for providing wash fluid to the various spray devices and manifolds at any location within dishwashing appliance 100.

Each spray arm assembly 134, 140, 142, integral spray manifold 144, filter clean assembly 145, or other spray device may include an arrangement of discharge ports or orifices for directing wash fluid received from circulation pump 152 onto dishes or other articles located in wash chamber 106. The arrangement of the discharge ports, also referred to as jets, apertures, or orifices, may provide a rotational force by virtue of wash fluid flowing through the discharge ports. Alternatively, spray assemblies 134, 140, 142, 145 may be motor-driven, or may operate using any other suitable drive mechanism. Spray manifolds and assemblies may also be stationary. The resultant movement of the spray assemblies 134, 140, 142, 145 and the spray from fixed manifolds provides coverage of dishes and other dishwasher contents with a washing spray. Other configurations of spray assemblies may be used as well. For instance, dishwasher 100 may have additional spray assemblies for cleaning silverware, for scouring casserole dishes, for spraying pots and pans, for cleaning bottles, etc.

In some embodiments, an exemplary filter assembly 210 is provided. As shown, in exemplary embodiments, filter assembly 210 is located in the sump 138 (e.g., to filter fluid to circulation assembly 150). Generally, filter assembly 210 removes soiled particles from the fluid that is recirculated through the wash chamber 106 during operation of dishwashing appliance 100. In exemplary embodiments, filter assembly 210 includes both a first filter 212 (also referred to as a “coarse filter”) and a second filter 214 (also referred to as a “fine filter”).

In some embodiments, the first filter 212 is constructed as a grate having openings for filtering fluid received from wash chamber 106. The sump 138 includes a recessed portion upstream of circulation pump 152 or a drain pump 168 and over which the first filter 212 is removably received. In exemplary embodiments, the first filter 212 operates as a coarse filter having media openings in the range of about 0.030 inches to about 0.060 inches. The recessed portion may define a filtered volume wherein debris or particles have been filtered by the first filter 212 or the second filter 214.

In additional or alternative embodiments, the second filter 214 is provided upstream of circulation pump 152 or drain pump 168. Second filter 214 may be non-removable or, alternatively, may be provided as a removable cartridge positioned in a tub receptacle formed in sump 138. For instance, the second filter 214 may be removably positioned within a collection chamber defined by the tub receptacle. The second filter 214 may be generally shaped to complement the tub receptacle. For instance, the second filter 214 may include a filter wall that complements the shape of the tub receptacle. In some embodiments, the filter wall is formed from one or more fine filter media. Some such embodiments may include filter media (e.g., screen or mesh, having pore or hole sizes in the range of about 50 microns to about 600 microns). When assembled, the filter wall may define an internal chamber. In optional embodiments, a top portion of fine filter positioned above the internal chamber may define one or more openings of the filter wall, thereby permitting fluid to flow into the internal chamber without passing through the first filter 212 or the fine filter media of the filter wall of the second filter 214.

During operation of some embodiments (e.g., during or as part of a wash cycle or rinse cycle), circulation pump 152 draws wash fluid in from sump 138 through filter assembly (e.g., through first filter 212 or second filter 214). Thus, circulation pump 152 may be downstream of filter assembly 210.

In optional embodiments, circulation pump 152 urges or pumps wash fluid (e.g., from filter assembly 210) to a diverter 156. In some such embodiments, diverter 156 is positioned within sump 138 of dishwashing appliance 100). Diverter 156 may include a diverter disk (not shown) disposed within a diverter chamber 158 for selectively distributing the wash fluid to the spray arm assemblies 134, 140, 142, or other spray manifolds. For instance, the diverter disk may have a plurality of apertures that are configured to align with one or more outlet ports (not shown) at the top of diverter chamber 158. In this manner, the diverter disk may be selectively rotated to provide wash fluid to the desired spray device.

In exemplary embodiments, diverter 156 is configured for selectively distributing the flow of wash fluid from circulation pump 152 to various fluid supply conduits—only some of which are illustrated in FIG. 2 for clarity. In certain embodiments, diverter 156 includes four outlet ports (not shown) for supplying wash fluid to a first conduit for rotating lower spray arm assembly 134, a second conduit for supplying wash fluid to filter clean assembly 145, a third conduit for spraying an auxiliary rack such as the silverware rack, and a fourth conduit for supply mid-level or upper spray assemblies 140, 142 (e.g., primary supply conduit 154).

Drainage of soiled wash fluid within sump 138 may occur, for instance, through drain assembly 166 (e.g., during or as part of a drain cycle). In particular, wash fluid may exit sump 138 through a drain and may flow through a drain conduit 167. In some embodiments, a drain pump 168 downstream of sump 138 facilitates drainage of the soiled wash fluid by urging or pumping the wash fluid to a drain line external to dishwasher 100. Drain pump 168 may be downstream of first filter 212 or second filter 214. Additionally or alternatively, an unfiltered flow path may be defined through sump 138 to drain conduit 167 such that an unfiltered fluid flow may pass through sump 138 to drain conduit 167 without first passing through either first filter 212 or second filter 214.

Although a separate recirculation pump 152 and drain pump 168 are described herein, it is understood that other suitable pump configurations (e.g., using only a single pump for both recirculation and draining) may be provided.

In certain embodiments, dishwasher 100 includes a controller 160 configured to regulate operation of dishwasher 100 (e.g., initiate one or more washing operations). Controller 160 may include one or more memory devices and one or more microprocessors, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with a washing operation that may include a wash cycle, rinse cycle, or drain cycle. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In some embodiments, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor. Alternatively, controller 160 may be constructed without using a microprocessor (e.g., using a combination of discrete analog or digital logic circuitry—such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like—to perform control functionality instead of relying upon software).

Controller 160 may be positioned in a variety of locations throughout dishwasher 100. In optional embodiments, controller 160 is located within a control panel area 162 of door 116 (e.g., as shown in FIGS. 1 and 2 ). Input/output (“I/O”) signals may be routed between the control system and various operational components of dishwasher 100 along wiring harnesses that may be routed through the bottom of door 116. Typically, the controller 160 includes a user interface panel/controls 164 through which a user may select various operational features and modes and monitor progress of dishwasher 100. In some embodiments, user interface 164 includes a general purpose I/O (“GPIO”) device or functional block. In additional or alternative embodiments, user interface 164 includes input components, such as one or more of a variety of electrical, mechanical or electro-mechanical input devices including rotary dials, push buttons, and touch pads. In further additional or alternative embodiments, user interface 164 includes a display component, such as a digital or analog display device designed to provide operational feedback to a user. When assembled, user interface 164 may be in operative communication with the controller 160 via one or more signal lines or shared communication busses.

It should be appreciated that the invention is not limited to any particular style, model, or configuration of dishwasher 100. The exemplary embodiment depicted in FIGS. 1 and 2 is for illustrative purposes only. For instance, different locations may be provided for user interface 164, different configurations may be provided for rack assemblies 122, 124, 126, different spray arm assemblies 134, 140, 142 and spray manifold configurations may be used, and other differences may be applied while remaining within the scope of the present disclosure.

Turning especially to FIG. 3 , a close up, cross sectional view of sump 138 and a pressure sensor 200 is provided. In some instances, portions of dishwasher 100 may become obstructed or clogged (e.g., at filter assembly 210). Accordingly, and in accordance with exemplary aspects of the present disclosure, dishwasher 100 utilizes outputs from pressure sensor 200 to monitor or prevent obstructions or clogs.

In some embodiments, pressure sensor 200 mounted to sump 138. Pressure sensor 200 is operatively configured to detect a liquid level L within sump 138 and communicate the liquid level L to controller 160 (FIG. 2 ) via one or more signals. Thus, pressure sensor 200 and controller 160 are generally provided in operative communication.

During use, pressure sensor 200 may transmit signals to controller 160 for instance, as a frequency, as an analog signal, or in another suitable manner or form that can be received by controller 160 to detect a pressure value (e.g., as a value of relative pressure or hydrostatic pressure, such as value in units of mmH₂O). In certain embodiments, pressure sensor 200 is configured to sense the height H of the wash fluid above pressure sensor 200 along the vertical direction V (e.g., by detecting the pressure on pressure sensor 200). For instance, pressure sensor 200 may include a pressure plate that is generally acted on by the pressure of the wash fluid within sump 138. As the liquid level L rises, the pressure plate is pushed upward along the vertical direction V and, thus, compresses air trapped within the housing and a diaphragm of pressure sensor 200. Compression may cause the diaphragm to flex or alter its position. As a result of the pressure and consequent movement of the diaphragm, a permanent magnet attached to the diaphragm may change its position in relation to a Hall-effect transducer. The transducer delivers one or more electrical signals proportional to the magnetic field of the magnet. Optionally, the signals from pressure sensor 200 may be linearized, digitized, or amplified before being sent to controller 160 for processing. Additionally or alternatively, the pressure sensor 200 may include a printed circuit board (PCB) board to electrically connect the various electrical components of pressure sensor 200. Moreover, pressure sensor 200 can be any suitable type of sensor capable of sensing the liquid level L within dishwasher 100.

Notably, as an upstream sensor (e.g., upstream of circulation pump 152 or drain pump 168), signals from pressure sensor 200 may be used or configured for additional detections, such as detection of overfill or flood event (e.g., as would be caused by an out-of-level condition, an inlet water valve failure, or a drain pump failure) that would otherwise go undetected by a pressure sensor downstream (i.e., on the high-pressure side) of circulation pump 152 or drain pump 168.

Turning now to FIG. 4 , various methods (e.g., method 400) for operating a dishwashing appliance are illustrated. Such methods may be used to operate any suitable dishwashing appliance. As an example, method 400 may be used to operate dishwashing appliance 100 (FIG. 1 ). The controller 160 (FIG. 2 ) may be programmed to implement some or all of method 400 (e.g., as or as part of a washing operation).

Advantageously, systems or methods in accordance with the present disclosure may detect or address siphon conditions within a dishwashing appliance (e.g., without requiring user knowledge or intervention). Moreover, such systems or methods may prevent wasted water, excessive noise, or damage to certain features (e.g., a drain pump).

At 410, the method 400 includes activating the drain pump for an activation period. Such activation may be, for example, part of a drain cycle. In certain embodiments, 410 follows (e.g., occurs subsequent to) a fill segment or phase of a wash cycle or rinse cycle. For instance, 410 may occur after a volume of water or wash fluid has been supplied to wash chamber. Thus, as would be understood, drain pump may be directed to rotate or otherwise move to motivate the volume of water or wash fluid from the wash chamber (e.g., at the sump). Moreover, as described above, drain pump may be disposed downstream from the sump and, thereby, generate a negative pressure or vacuum at the sump. As the drain pump is activated (i.e., during the activation period), the circulation pump may be deactivated (i.e., held in an inactive state).

Optionally, the activation period of 410 may be defined as a predetermined time interval. In turn, the drain may be activated (e.g., directed to the active state) for a predetermined span of time (e.g., initial span of time). Additionally or alternatively, the activation period may be a continuous activation period such that, for a predetermined period of time, the drain pump is directed to operate uninterrupted in an attempt to motivate a substantially continuous or non-pulsated fluid flow (e.g., as in a continuous flow state).

At 420, the method 400 includes deactivating the drain pump for a deactivation period. In particular, 420 follows 410 and, thus, requires deactivating the drain pump (i.e., directing or holding the drain pump to or in an inactive state) after the activation period. For instance, a current or voltage to the motor of the drain pump may be halted. As the drain pump is deactivated (i.e., during the deactivation period), the circulation pump may also be deactivated (i.e., held in an inactive state). For instance, all pumps in fluid communication with the wash chamber may be directed to or maintained in an inactive state such that no wash fluid is actively urged or pumped therethrough during 420. Additionally or alternatively, a water valve configured to direct water to the wash chamber, as described above, may be closed such that no new water is provided to wash chamber during the deactivation period. Optionally, the deactivation period of 420 may be defined as a predetermined time interval (e.g., different from that of the activation period). In turn, the drain may be deactivated for a predetermined span of time. In some such embodiments, the deactivation period is between 10 seconds and 120 seconds or between 15 seconds and 60 seconds.

At 430, the method 400 includes detecting a first water condition upstream from the drain pump. In particular, 430 may occur during the deactivation period (e.g., while the drain pump is in an inactive state). In some embodiments, the first water condition is a first pressure (P1). For instance, P1 may be detected at a pressure sensor mounted within the sump (e.g., as described above). Thus, 430 may include detecting a pressure (P1) (e.g., as a value of relative pressure or hydrostatic pressure, such as value in units of mmH₂O) at the pressure sensor upstream from the drain pump while maintaining the drain pump in an inactive state.

At 440, the method 400 includes detecting a second water condition upstream from the drain pump. Specifically, 440 may occur after (i.e., following) 430. Nonetheless, 440 may still occur during the deactivation period. In certain embodiments, the time between 440 and 430 is set in advance (i.e., predetermined). For instance, 440 may occur after a set period of time or interval following 430. In turn, the method 400 may include measuring expiration of a set period following detecting the first water condition. In some such embodiments, 440 is prompted or otherwise is performed in response to expiration of the set period.

In some embodiments, the first water condition is a second pressure (P2). For instance, P2 may be detected at a pressure sensor mounted within the sump (e.g., as described above). Thus, 440 may include detecting a pressure (P2) (e.g., as a value of relative pressure or hydrostatic pressure, such as value in units of mmH₂O) at the pressure sensor upstream from the pump while maintaining the drain pump in an inactive state.

At 450, the method 400 includes comparing the second water condition to the first water condition. Specifically, 450 may include determining the difference between the first and second water conditions. Such a difference may be determined as a fixed value or a relative value (e.g., percentage). Optionally, a threshold condition may be provided for the difference between the first and second water conditions. Thus, 450 may include determining whether this difference meets (e.g., is greater than or equal to) or, alternatively, fails to meet (e.g., is less than) the threshold condition. In some embodiments, the threshold condition is a variable threshold. Thus, 450 may include determining the second water condition is less than the variable threshold relative to the first water condition.

In exemplary embodiments, the variable threshold is set as a relative value that is contingent on the first water condition. For instance, the variable threshold may be calculated as a predetermined percentage of the first water condition (e.g., as part of 450). The predetermined percentage may be less than 100%. Thus, the variable threshold may be less than a value of the first water condition. As an example, the variable threshold (RT) may be calculated by multiplying the first water condition (e.g., P1) times the predetermined percentage (EP). In other words, in some embodiments, RT=(P1*EP). Once RT is calculated, the second water condition (e.g., P2) may be directly comparted to RT. Optionally, a determination (e.g., binary determination) may be made as to whether the second water condition meets or exceeds RT. Thus, 450 may include a determination that either P2≥RT or, alternatively, P2<RT.

At 460, the method 400 includes directing the drain pump based on the comparison of the second water condition to the first water condition. As an example, under non-siphon conditions, uninterrupted continuation of a larger washing operation is permitted following 450. By contrast, under siphon conditions, a modified cycle is directed (e.g., before continuing with the larger washing operation).

In some embodiments, a non-siphon condition is identified or indicated by 450. Optionally, the non-siphon condition may be identified by (e.g., in response to) a determination at 450 that the second water condition is greater than or equal to the variable threshold relative to the first water condition. For instance, it may be determined that P2≥RT. In response to the non-siphon condition, continuation of a larger washing operation may be permitted. As an example, 460 may include maintaining the drain pump in the deactivated state (e.g., continuously beyond or past the deactivation period). Additionally or alternatively, a new volume of water or wash fluid may be directed to the wash chamber and the circulation pump may be activated or reactivated as part of a subsequent rinse or wash cycle, as would be understood.

In certain embodiments, a siphon condition is identified or indicated by 450. Optionally, the non-siphon condition may be identified by (e.g., in response to) a determination at 450 that the second water condition is less than the variable threshold relative to the first water condition. For instance, it may be determined that P2<RT. In response to a siphon condition, a modified cycle may be initiated or directed. As an example, 460 may include reactivating the drain pump (e.g., again activated or directed to the activate state, as described above). Optionally, reactivating the drain pump may be for a reactivation period.

Optionally, the reactivation period of 460 may be defined as a predetermined time interval. In turn, the drain may be reactivated (e.g., directed to the active state) for a predetermined span of time (e.g., secondary span of time). Additionally or alternatively, the reactivation period may be a continuous activation period such that, for a predetermined period of time for reactivation, the drain pump is directed to operate uninterrupted in an attempt to motivate a substantially continuous or non-pulsated fluid flow (e.g., as in a continuous flow state). Optionally, the reactivation period may be between 2 seconds and 60 seconds or between 5 seconds and 15 seconds.

Following reactivation, the drain pump may be deactivated (e.g., for a second deactivation). For instance, 460 may include deactivating, again, the drain pump. In particular, deactivation following reactivation may be in response to expiration of the predetermined time period for reactivation. Thus, a current or voltage to the motor of the drain pump may be halted.

Notably, following the reactivation or deactivation of the drain pump, an air break or slug may be generated in the drain line for the drain pump.

Following or in tandem with the second deactivation, the washing operation may be resumed. For instance, a new volume of water or wash fluid may be directed to the wash chamber. Additionally or alternatively, the circulation pump may be activated or reactivated as part of a subsequent rinse or wash cycle, as would be understood (e.g., while holding the drain pump in the inactive state).

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

1. A dishwashing appliance, comprising: a cabinet; a tub positioned within the cabinet and defining a wash chamber for receipt of articles for washing; a spray assembly positioned within the wash chamber; a drain pump in fluid communication with the wash chamber; and a controller in operative communication with the drain pump, the controller being configured to initiate a washing operation, the washing operation comprising activating the drain pump for an activation period, deactivating the drain pump for a deactivation period, detecting a first water condition upstream from the drain pump during the deactivation period, detecting, following detecting the first water condition, a second water condition upstream from the drain pump during the deactivation period, comparing the second water condition to the first water condition, and directing the drain pump based on the comparison of the second water condition to the first water condition.
 2. The dishwashing appliance of claim 1, wherein the first water condition is a first pressure (P1), and wherein the second water condition is a second pressure (P2).
 3. The dishwashing appliance of claim 2, further comprising: a pressure sensor disposed upstream from the drain pump, wherein the first pressure is detected at the pressure sensor, and wherein the second pressure is detected at the pressure sensor.
 4. The dishwashing appliance of claim 1, wherein comparing the second water condition to the first water condition comprises determining the second water condition is less than a variable threshold relative to the first water condition.
 5. The dishwashing appliance of claim 1, wherein directing the drain pump comprises reactivating the drain pump.
 6. The dishwashing appliance of claim 5, wherein reactivating the drain pump is for a reactivation period.
 7. The dishwashing appliance of claim 6, wherein the reactivation period is limited to a predetermined time period for reactivation, and wherein the washing operation further comprises deactivating, again, the drain pump in response to expiration of the predetermined time period for reactivation.
 8. The dishwashing appliance of claim 1, wherein the washing operation further comprises activating a circulation pump following reactivating the drain pump.
 9. The dishwashing appliance of claim 1, wherein the washing operation further comprises measuring expiration of a set period following detecting the first water condition, wherein detecting the second water condition is in response to measuring expiration of the set period.
 10. A method of operating a dishwashing appliance comprising a sump and a drain pump downstream from the sump, the method comprising: activating the drain pump for an activation period; deactivating the drain pump for a deactivation period; detecting a first water condition upstream from the drain pump during the deactivation period; detecting, following detecting the first water condition, a second water condition upstream from the drain pump during the deactivation period; comparing the second water condition to the first water condition; and directing the drain pump based on the comparison of the second water condition to the first water condition.
 11. The method of claim 10, wherein the first water condition is a first pressure (P1), and wherein the second water condition is a second pressure (P2).
 12. The method of claim 11, wherein the first pressure is detected at a pressure sensor mounted within the sump, and wherein the second pressure is detected at the pressure sensor.
 13. The method of claim 10, wherein comparing the second water condition to the first water condition comprises determining the second water condition is less than a variable threshold relative to the first water condition.
 14. The method of claim 10, wherein directing the drain pump comprises reactivating the drain pump.
 15. The method of claim 14, wherein reactivating the drain pump is for a reactivation period.
 16. The method of claim 15, wherein the reactivation period is limited to a predetermined time period for reactivation, and wherein the method further comprises deactivating, again, the drain pump in response to expiration of the predetermined time period for reactivation.
 17. The method of claim 10, further comprising: activating a circulation pump following reactivating the drain pump.
 18. The method of claim 10, further comprising: measuring expiration of a set period following detecting the first water condition, wherein detecting the second water condition is in response to measuring expiration of the set period. 